1. Field of the Invention
The present invention relates to a new apparatus and method for removing deposits from the internal surfaces of process equipment. More particularly the present invention relates to a gas explosion apparatus and process used to drive a shock wave through objects to be cleaned. The movement of the shock wave through the object dislodges deposits inside the objects.
2. Background
Fouling of the internal surfaces of process equipment is a common problem. In many instances this fouling occurs through a build-up of deposits or particles adhering to the internal surfaces. This fouling usually reduces the efficiency of the piece of equipment Thus, cleaning the internal surfaces is necessary to maintain peak efficiency in the equipment.
One generally known method for cleaning utilizes pressure pulses to dislodge deposits The pressure pulse cleans by first subjecting the deposit laden surface to a very high pressure and then to a much lower pressure. The pressure differential causes the deposits to expand and to become dislodged from the surface. To clean the internal surface of a piece of equipment the pressure pulse must move through equipment creating a moving pressure differential.
Typically pressure pulses are produced by releasing short bursts of high pressure gas through a valve. Gas explosion has also been utilized as a method for producing a shock wave. U.S. Pat. No. 4,089,702 to Enoksson et. al., hereinafter Enoksson, discloses detonating an explosive gas mixture to produce a shock wave which can be used to dislodge particles such as sand and scale from internal surfaces of objects The method of Enoksson, however, has several disadvantages. Enoksson teaches sealing off the outlet means of the equipment to be cleaned and filling the internal cavity of the equipment with an explosive gas. This method disadvantageously requires the halting of any process being performed by the equipment being cleaned. The method also disadvantageously requires cleaning large pieces of equipment in segments, thereby requiring valves or other means in the equipment to seal off the different segments and permit filling the segment with explosive gas. Another disadvantage of Enoksson is that the explosion is not precisely controllable.
U.S. Pat. No. 4 642,611 to Koerner, hereinafter Koerner, discloses a sound engine, for generating sonic waves by igniting a gas. This sound engine, however, is disadvantageous for use in cleaning process equipment. Koerner teaches acoustically cleaning equipment by creating a loud resonant frequency which vibrates or shakes the piece of equipment being cleaned. The vibration or shaking of the equipment causes particles to dislodge from the internal surfaces of the equipment. Koerner also teaches this resonate frequency is a substantially continuous sound. The vibration cleaning of Koerner is disadvantageous or unsuitable, however, for cleaning large pieces of process equipment. Most large pieces of process equipment are rigidly mounted in a manner which makes vibrating the equipment difficult. Also, a large piece of equipment would require the generation of an extremely loud sound to induce vibration for cleaning by Koerner's method. This continuous loud sound would be unpleasant and/or dangerous for people living or working near the equipment being cleaned Koerner also suggests that any process being performed by the piece of equipment to be cleaned must be halted or finished before cleaning begins,
Accordingly, one object of the present invention is to overcome the disadvantages of known pulse cleaning equipment by providing an apparatus and method for cleaning which can be used in a piece of process equipment during the process being performed by the equipment without the equipment having to be frequently dismantled.
Another object of the present invention is to provide an apparatus for exploding a gas to produce a shock wave which will move through a piece of process equipment and dislodge deposits and particles adhering to the inner surface of the equipment.
A further object of the present invention is to provide an apparatus which allows for a controlled gas explosion to generate a shock wave.
A still further object of the present invention is to provide an apparatus for exploding a gas to produce a shock wave which can be directed in a certain direction.
A still further object of the present invention is to provide an apparatus for exploding a gas in which the means for igniting the gas do not require frequent replacement.
Other objects and advantages of the present invention will become apparent in the following description of the invention.